Sanicro® 28 for OCTG

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Sandvik materials.

Cold hardened (cold worked) seamless tube and pipe

Full details on sizes, finishes and mechanical properties are available on request.Email: stmo.smt@sandvik.com

Mechanical properties

At20°C (68°F)

Metric units and Imperial units

Grade

Proof strength

Tensile strength

Elong.

Hardness

Rp0.2a)

Rm

A2"

HRC

MPa

ksi

MPa

ksi

%

min

min

min

max

PSL-1 Sanicro 28-110

760 - 965

110 - 140

795

115

11

35

PSL-1 Sanicro 28-125

860 - 1035

125 - 150

895

130

10

37

PSL-2 Sanicro 28-110

760 - 965

110 - 140

795

115

11

33

PSL-2 Sanicro 28-125

860 - 1000

125 - 145

895

130

10

35

1 MPa = 1 N/mm2a) Rp0.2 correspond to 0.2% offset yield strength.

At high temperatures

Cold-worked Sanicro 28 also displays very good mechanical properties at higher temperatures. Further information is available on request. Email:stmo.smt@sandvik.com

Metric units Imperial units

Temperature, °C

De-rating factor*

Temperature, °F

De-rating factor*

20

1.00

68

1.00

50

0.97

100

0.98

100

0.92

200

0.93

150

0.89

300

0.89

200

0.88

400

0.88

250

0.87

500

0.87

*) Approximate yield strength at temperature is received by multiplying the corresponding de-rating factor and yield strength at 20oC (68oF).

Impact strength

Due to its austenitic microstructure, Sanicro® 28 has very good impact strength, both at room temperature and at lower temperatures. Tests have demonstrated that the steel readily fulfills the requirements in accordance with ISO 13680 (min. 40 J at -10oC (50oF)).

Physical properties

Physical properties of cold-worked Sanicro 28.

Density: 8.0 g/cm3, 0.29 lb/in3

Relative magnetic permeability

1.003 (approximate value)

Metric units Imperial units

Thermal conductivity

Metric units

Imperial units

Temperature, °C

W/(m °C)

Temperature, °F

Btu/(ft h °F)

20

11

68

6.5

50

11

100

6.5

100

12

200

7

150

13

300

7.5

200

14

400

8.5

250

15

500

9

300

16

600

9.5

Specific heat capacity

Metric units

Imperial units

Temperature, °C

J/kg °C

Temperature, °F

Btu/lb °F

20

460

68

0.11

50

470

100

0.11

100

480

200

0.12

150

495

300

0.12

200

505

400

0.12

250

515

500

0.12

300

525

600

0.13

Resistivity

Metric units

Imperial units

Temperature, °C

µΩm

Temperature, °F

µΩin.

20

0.98

68

38.7

100

1.00

200

39.3

150

1.00

300

39.4

200

1.01

400

39.9

250

1.04

500

41.3

300

1.10

600

44.2

Thermal expansion 1)

Metric units

Imperial units

Temperature, °C

Per °C

Temperature, °F

Per °F

30-50

13

86-120

7.5

30-100

14.5

86-200

8

30-150

15

86-300

8.5

30-200

15.5

86-400

8.5

30-250

15.5

86-500

8.5

30-300

15.5

86-600

8.5

1) Mean values in temperature ranges (×10-6)

Modulus of elasticity 1)

Metric units

Imperial units

Temperature, °C

MPa

Temperature, °F

ksi

20

195

68

28.3

100

190

200

27.6

200

182

400

26.3

300

174

600

25.1

1) (×103)

Poisson´s ratio

The Poisson's ratio is 0.29 for Sanicro® 28 at room temperature.

Corrosion resistance

Pitting corrosion

Sanicro® 28 can withstand high temperatures in aggressive environments without pitting. A recognized method of ranking a material's susceptibility to localized corrosion is by means of the PRE number (Pitting Resistance Equivalent). This PRE number is based on the contents of chromium, molybdenum and nitrogen in the alloy according to the following formula:PRE = %Cr + 3.3 × %Mo + 16 × %N

A PRE number is the relative measure of a material's ability to resist pitting corrosion in chloride containing environments. Sanicro®28 has a minimum PRE number of 38, which confirms its high resistance to pitting corrosion when chlorides are present.

Critical pitting temperature (CPT) was determined on cold worked Sanicro® 28 per modified ASTM G150. The temperature of the test solution was started at 20°C, and heated at a rate of 1 °C/min. The tests were carried out in NaCl solutions of three chloride concentrations without pH adjustment; and also in 3 wt% Cl- with three fixed pH. The solution of 1.7 liters was purged with nitrogen during the test. The assessments were carried out at a potential of +634 mV vs. Ag/AgCl on triplicate specimens per test environment. The high CPT suggests the high pitting corrosion resistance of the material in the environments tested.

Figure 2. Critical pitting temperature (CPT) as a function of pH for cold worked Sanicro® 28 in a 3% Cl- solution. The potential was +634 mV vs Ag/AgCl.

Stress corrosion cracking (SCC)

Environmental assisted cracking, especially in the presence of hydrogen sulphide (H2S), is one of the more serious forms of corrosion in sour environments. Failure of tubing by environmental assisted cracking can occur rapidly without any warning. For that reason, the prevention of this form of corrosion must be considered when selecting tubing materials for sour wells.

According to ISO 15156-3 (2015), cold worked Sanicro® 28 belongs to type 4c material which can be safely used in the limited environmental combinations of temperature and H2S in order to avoid the risk of SCC. Laboratory test data shows that cold worked Sanicro® 28 tube materials are not susceptible to SCC in sour environments, even outside of the limits for 4c type materials.

Figure 3: SCC testing data of cold worked Sanicro® 28 tube materials in sour environments in comparison with the ISO 15156-3 limits for 4c type materials. The SCC testing has been performed on Sanicro® 28 tube materials stressed at 100% actual yield strength (AYS) using tensile constant load per NACE TM0177 method A, C-ring per NACE TM0177 method C, as well as slow strain rate test (SSRT) per NACE TM0198 at strain rate of 4×10-6 in/in/sec. Sanicro® 28 showed good ductility in the tested sour environments with no failures.

Stress corrosion cracking tests have also been performed in the presence of elemental sulfur. Cold worked Sanicro® 28 tube with an Rp0.2 value of 889 MPa (129 ksi) has been tested. The tests were performed, according to NACE TM0177, with tensile specimens stressed to 100% of the actual yield strength.

Temperature

pH2S

pCO2, psi

Chlorides (Cl-)

Elemental sulfur

Stress corrosion cracking

°C (°F)

psi (MPa)

(MPa)

mg/l

g/l

140 (284)

2200 (15.2)

1000 (6.9)

102000

1

No

160 (320)

2200 (15.2)

1000 (6.9)

102000

1

No

170 (338)

2200 (15.2)

1000 (6.9)

102000

1

No

160 (320)

2200 (15.2)

1000 (6.9)

299000

1

No

Heat treatment

Tubes for downhole oil and gas applications are delivered in the high strength, cold hardened condition. They are not annealed after cold working.

Fabrication

Sanicro® 28 tubes are supplied in the cold worked condition and are intended for use with threaded connections.

Applications

Sanicro® 28 is used for high strength downhole production tubing, casing, and liners in sour gas wells. This includes environments with high temperatures, high partial pressures of CO2 and H2S, and high chloride concentrations.

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Sandvik materials.